"Fentanyl is the biggest threat we're facing right now," said a federal agent with the Drug Enforcement Administration, who is unable to reveal his name. "It's being mixed in with everything from cocaine, to caffeine, to animal tranquilizer. The potency is so high, something seven or eight grains of salt size - you inhale that and you're immediately starting to have trouble breathing."

A synthetic opioid, fentanyl is 30 to 50 times more powerful than heroin, the DEA says, making exposure for first responders highly risky as well. That is why they now have to wear thick airtight suits when fentanyl is spotted during medical responses or at crime scenes.

"It's an epidemic," said DEA Special Agent Jamie Nassour. "Whatever point might be compromised in that suit, they (first responders) can go down instantaneously."

Nassour suited up with Eyewitness News for a special training assignment, so we could show you what they experience on these calls.

It can take up to an hour to put on all of the "Level A" hazardous material equipment. That's the highest level of protection.

First, we started with the base of the thick suit, the boots, and inner belts. Medics then checked our vital signs, before masks were put on our heads and adjusted. Oxygen tanks weighing 30 pounds were then checked, put on and belted to our backs. We also put on gloves, and were then fully zipped in -- air tanks and all -- into the airtight suits.

"How much air do you get in a tank like this?" I asked.

"Thirty to 40 minutes at most," the agent said.

That is why we moved quickly to a drug training scene laid out by the DEA in a mobile home. For training purposes, the white powder used was baby powder.

"Your scenario is someone has been found dead in this residence," a DEA agent announced, "and there's an unknown powder all around where his body was. The girlfriend pulled him out. They're going to send you in, and you're going to assess what it possibly could be. We think it might be fentanyl."

In that brief 15 minutes inside the trailer, there was no describing the intense 100-degree heat inside that green suit, and the difficulty I had walking in it, while also trying to see my surroundings through a small window in the mask and the suit.

On top of that, I was given an electronic device that detects whether the powder on sight was fentanyl. While trying to focus on the testing, a loud bang suddenly went off in the room. The DEA had just thrown us a curve ball: a simulated explosion, and Special Agent Nassour went down.

My job then was to drag her out, and she did not help me, acting as dead weight, with both of us wearing those heavy suits. It was one of the most difficult things I have ever done.

"That simulated if there was some type of explosion or chemicals there," said a DEA agent, "and that has happened before."

In May, an officer in East Liverpool, Ohio was exposed to fentanyl during an arrest and had to be hospitalized from an overdose. He wore gloves and a mask during the search of the suspect's car, but some of the fentanyl powder accidentally got onto the officer's shirt. When he brushed it off at the police station, the officer suddenly fell ill.

Two New Jersey officers also accidentally inhaled fentanyl during a drug bust, and one of the officers said, "You actually felt like you were dying. You couldn't breathe."

In July, Santa Ana police officers also came face to face with fentanyl, responding to a deadly overdose at an apartment complex. They called in the Orange County Fire Authority hazardous materials team to handle the situation.

Toward the end of our training, low oxygen tank level alarms start sounding while officers were going through the extensive decontamination process. They must be hosed down and scrubbed from head to toe, to make sure every grain of fentanyl is washed away.

The DEA says one fentanyl lab can take an entire day to clear, with round after round of agents suiting up and going in, through 40 minute waves, until the scene is finally clean.

"Breaking down a lab is extremely tiresome, and difficult, and stressful," Nassour said. "What we wear to keep ourselves safe is so extreme, that the idea that someone would be willing and wanting to ingest this for a high is almost unfathomable."